The US has warned Iran that the installation of next generation equipment at a nuclear plant would be "a provocative step".

It follows a report from the UN's nuclear watchdog.

The IAEA says Iran has begun installing advanced centrifuges at the Natanz facility.

If launched successfully, the West fears it could help to build a nuclear weapon.

Tehran insists its programme is for peaceful purposes only.

The report comes just days before Iran meets world powers in Kazakhstan to discuss its nuclear programme.

Hillary Mann Leverett, the author of 'Going to Tehran - Why the United States must come to terms with the Islamic Republic of Iran' told Al Jazeera: "Iran is doing what it has been doing for years, which is going forth with its nuclear programme - increasing the number of centrifuges.

"In 2003, Iran was spinning zero centrifuges, today they are spinning 8,000 centrifuges - they are just continuing their march toward mastering the fuel cycle and having as complete a nuclear programme as they possibly can," she said.

White House spokesman Jay Carney warned Iran that it would face further pressure and isolation if it fails to address international concerns about its nuclear programme in the February 26 talks with world powers in the Kazakh city of Almaty.

"Washington, in particular, is really on a collision course with these talks," Leverett told Al Jazeera.

"This is a collision course that will really in the end just discredit engagement and leave us with very few options other than more coercion and ultimately war," she said.